Since you have one of them setup for the 29 inch wheel you could just switch the internals. Then you would not have to change the oil in the air coil that used for tuning. However, it is not difficult to change the amount of oil in the air coil that then changes the progressive compression of the fork.

1. I position my bike so the fork is horizontal so when you remove the internals the bath oil doesn't run out. There is supposed to be about 10 ml of oil in the fork housing for bath oil. So spilling this on the floor is not a big mess but why go there if you don't have to. I put my bike in a stand where I can rotate the bike. I have also put the bike on the floor and positioned the pedals to get the fork horizontal. I put a couple of sandwich zip lock bags on the fork legs to catch the oil and then position them vertical.
2. There is a little Phillips screw on the knob on top of the oil damper. Be careful not to lose this. I keep the screw driver on the screw while I lift the knob off. I repeat this when putting the knob back on. Put the screw driver on the screw before putting the knob on the stem.
3. Release the air pressure in the air coil.
4. Remove the 10mm bolts at the top of each leg. After the air valve is a little loose then finish unscrewing it by hand while pulling on it a little keep the air damper rod fully engaged in the top cap. There is an o-ring on this air valve bolt than can get tore up if you donít remove this carefully. Been there done that.
5. I have a paper towel in one hand to wipe the oil while I pull the complete oil damper and air coil out with the other hand. Keep the air coil up right or horizontal or the tuning oil could run out from the 10mm rod since the air valve is off. I temporarily put the air valve back in since I have spilt this oil on the floor many times.
6. There should be a bottom out bumper on each 10mm rod. Sometimes these stick to the top of the fork housing. Sometimes they get chewed up.
7. The set from the 29er will have 1-1/2 inch spacers on the 10mm rods.
8. Switch the components and put it back together.
I would recommend you do a little servicing since you have them apart. I would stroke the oil damper to see if there is still air pressure and oil. Check the bath oil for quantity and cleanness. It would be easy to change the oil now. Clean motor oil is better than what might be in. I use what I have available. Mobil one 5 -30 is in some of mine now.
I am relatively new to the DUC32. I got my first one a year and a half ago. I have 8 of them now. I take them apart just to see how they work. I have made stanchions 1-1/2 inch longer instead of using the 1-1/2 inch spacers for my 29er setup. Then I get the full travel but I put more force on the fork housing and could break it and have a bad crash. But I like the ride with 6 inches of travel with a 29er. I have changed the internals to get 7 inches of travel. Had my first ride last night and I like it even better.
If you get into this and have a question you can call me at 256-603-9414.

Since you have one of them setup for the 29 inch wheel you could just switch the internals. Then you would not have to change the oil in the air coil that used for tuning. However, it is not difficult to change the amount of oil in the air coil that then changes the progressive compression of the fork.

1. I position my bike so the fork is horizontal so when you remove the internals the bath oil doesn't run out. There is supposed to be about 10 ml of oil in the fork housing for bath oil. So spilling this on the floor is not a big mess but why go there if you don't have to. I put my bike in a stand where I can rotate the bike. I have also put the bike on the floor and positioned the pedals to get the fork horizontal. I put a couple of sandwich zip lock bags on the fork legs to catch the oil and then position them vertical.
2. There is a little Phillips screw on the knob on top of the oil damper. Be careful not to lose this. I keep the screw driver on the screw while I lift the knob off. I repeat this when putting the knob back on. Put the screw driver on the screw before putting the knob on the stem.
3. Release the air pressure in the air coil.
4. Remove the 10mm bolts at the top of each leg. After the air valve is a little loose then finish unscrewing it by hand while pulling on it a little keep the air damper rod fully engaged in the top cap. There is an o-ring on this air valve bolt than can get tore up if you donít remove this carefully. Been there done that.
5. I have a paper towel in one hand to wipe the oil while I pull the complete oil damper and air coil out with the other hand. Keep the air coil up right or horizontal or the tuning oil could run out from the 10mm rod since the air valve is off. I temporarily put the air valve back in since I have spilt this oil on the floor many times.
6. There should be a bottom out bumper on each 10mm rod. Sometimes these stick to the top of the fork housing. Sometimes they get chewed up.
7. The set from the 29er will have 1-1/2 inch spacers on the 10mm rods.
8. Switch the components and put it back together.
I would recommend you do a little servicing since you have them apart. I would stroke the oil damper to see if there is still air pressure and oil. Check the bath oil for quantity and cleanness. It would be easy to change the oil now. Clean motor oil is better than what might be in. I use what I have available. Mobil one 5 -30 is in some of mine now.
I am relatively new to the DUC32. I got my first one a year and a half ago. I have 8 of them now. I take them apart just to see how they work. I have made stanchions 1-1/2 inch longer instead of using the 1-1/2 inch spacers for my 29er setup. Then I get the full travel but I put more force on the fork housing and could break it and have a bad crash. But I like the ride with 6 inches of travel with a 29er. I have changed the internals to get 7 inches of travel. Had my first ride last night and I like it even better.
If you get into this and have a question you can call me at 256-603-9414.

Wow 8 of them, how many bikes do you have.. !?

Thanks for the excellent write up, I feel much confident now in fact I'm going to try it this weekend if I can find the time.

Thanks again for sharing your know how in such a easy to understand terms, In fact I'm going to print it and have it next to me when I can the forks apart..

Your welcome, be cautious when putting back together. Donít over tighten the oil damper bolt or the air valve bolt. The end of the 10mm rods have teeth on them to bite into the top cap to keep from turning. Sometimes these donít bite and the 10mm rod turns while you are trying to tighten the bolt. I hit the end of my wrench with a rubber mallet when this happens.
Look at the inside end of the air coil 10mm rod. It has a smooth area before the threads start. This is where the o-ring on the air valve bolt seals. Make sure it is clean as well as the o-ring. I put a little grease on the o-ring. Ethan indicates these 10mm rods can get a little crack in them. Inspect them now so you know what a good one looks like.
When you put the air coil in try to get the 10mm rod fully engaged into the top cap. If it doesnít then try to screw the air valve bolt in just a turn or two and then try to pull the rod into the top cap.
The knob on top of the oil damper is really two knobs, the inner one is the rebound and the outer on is the lock-out. I keep these together when I take them off and on. There is an 0-ring on both of these. If the o-ring on the lock-out knob is a little loose it is more difficult to get the knob into the top cap. I just keep at it and eventually get it on. The end of the rebound shaft has two flat sides to engage into the rebound knob. You want to make sure the rebound knob is fully on this shaft before you tighten the little Phillips screw. Ethanís tip is to push down on the rebound knob and turn it counter clockwise. It should engage the rebound shaft and turn it to the end stop within two turns. Then you know it is on the shaft properly. This is when I tighten the little Phillips screw.
Take pictures while you disassemble.
Good luck with it.
Oh, I have too many bikes.

Your welcome, be cautious when putting back together. Donít over tighten the oil damper bolt or the air valve bolt. The end of the 10mm rods have teeth on them to bite into the top cap to keep from turning. Sometimes these donít bite and the 10mm rod turns while you are trying to tighten the bolt. I hit the end of my wrench with a rubber mallet when this happens.
Look at the inside end of the air coil 10mm rod. It has a smooth area before the threads start. This is where the o-ring on the air valve bolt seals. Make sure it is clean as well as the o-ring. I put a little grease on the o-ring. Ethan indicates these 10mm rods can get a little crack in them. Inspect them now so you know what a good one looks like.
When you put the air coil in try to get the 10mm rod fully engaged into the top cap. If it doesnít then try to screw the air valve bolt in just a turn or two and then try to pull the rod into the top cap.
The knob on top of the oil damper is really two knobs, the inner one is the rebound and the outer on is the lock-out. I keep these together when I take them off and on. There is an 0-ring on both of these. If the o-ring on the lock-out knob is a little loose it is more difficult to get the knob into the top cap. I just keep at it and eventually get it on. The end of the rebound shaft has two flat sides to engage into the rebound knob. You want to make sure the rebound knob is fully on this shaft before you tighten the little Phillips screw. Ethanís tip is to push down on the rebound knob and turn it counter clockwise. It should engage the rebound shaft and turn it to the end stop within two turns. Then you know it is on the shaft properly. This is when I tighten the little Phillips screw.
Take pictures while you disassemble.
Good luck with it.
Oh, I have too many bikes.

Thanks again for the compendium, I confess I'm getting kind of scare of making a "fatal" mistake but I will try to do it anyway, is just a shame is not a how to with photos..